A malfunctioning Skeleton, has very high combat stats and usually found wandering alone, not a good idea to fight without stats to match it. Encounterable in Obedience, Floodlands.
If you want to fight one, you should do it quick because of their spawn rate. You may encounter another one while fighting with 1st one, so your fight becomes harder. It is nice to use your own skeletons to fight broken one. In this way your squad won't need much time to heal and you won't have to sit and recover in such a dangerous territory.
Also, if you want to test your guys, the broken skeletons will be a nice experience.
Be careful! Water and swimming won't help you against skeletons!